The Speaker says the penalties to deal with anyone abusing Parliament's leave rules are inadequate and must be revised.
If MPs do not appear for 14 consecutive sitting days without good reason, the most their pay can be reduced is $10 per day.
Dr Lockwood Smith told Morning Report he does not want to imply he has concerns about Te Atutu MP Chris Carter's leave, but Mr Carter's case has brought the issue into the spotlight.
Dr Smith says, at the moment, he requires good evidence from MPs who are on long term sick leave that their illness is genuine.
He has asked the Law Commission to review the rules.
Earlier, Dr Smith said he had received a letter from Mr Carter's lawyer telling him the MP will return to Parliament on 4 October.
